Center locating device



March 20, 1962 D. HENDRIX 3,025,608

CENTER LOCATING DEVICE Filed Dec. 6, 1960 ATTORNEY dfiZSifiil Patented Mar. 20, 1962 free 3,025,608 CENTER LQCATING DEVICE Dewey Hendrix, 1306-A Salem Road, Morganton, N.C. Filed Dec. 6, 1960, Ser. No. 74,022 Claims. (Cl. 33-191) This invention pertains to center locating devices and, more particularly, to an improved center locating-device of the type having a plurality of arms extending outwardly from and movable relative to a central hub adapted to be positioned upon a work surface.

Devices of the type generally described in which the arms are rigidly constructed and extend completely through the hub are Well known in the art. Such devices are inherently incapable of being reduced in size to a diameter less than one-half the length of an arm thereof, as those skilled in the art are aware. This severely restricts the scope of their utility. For instance, they cannot be used to locate the center of a recessed or sunken work surface having a diameter less than onehalf the length of an arm, since the rigid arms prohibit placement of the device upon such a surface. Another area in which the utility of known devices having rigid arms is restricted, if not again altogether obviated, is in locating the center of work which is neither circular in cross-section or regularly polygonal in which the number of sides of the polygon is a multiple of four. In attempting to employ known centering devices with such other shapes, frequently some of the work engaging jaws or feet customarily carried upon the outer ends of the arms of devices of this general type prohibit placement of the hub upon the work and prohibit engagement of the other feet with the edges of the work.

Apart from their restricted scope, the known centering devices employing rigid arms are exceedingly cumbersome and awkward to store, carry, or use. Their minimum diameter of not less than one-half the length of an arm makes them of too great a width to be carried with facility either in the pocket of a workman or in an ordinary size tool kit. They are also excessively thick, since the height of the hubs of devices employing rigid arms must be relatively great to accommodate such arms in separate planes. Additionally, wherever such rigid arm devices might be stored or carried, the projecting arms tend to entangle themselves with any clothing, tools, or other material in their vicinity.

It is, therefore, a primary object of this invention to provide a device of the type described not subject to the above deficiencies, which may be carried, stored, and used with facility, and which enjoys an enhanced versatility of utilization. A centering device according to this invention can be constructed with a hub height only slightly greater than the height of an arm and may be reduced in size until its overall diameter is only slightly greater than that of its hub, permitting convenient storage and carrying thereof, and utilization upon interior or recessed work surfaces of small diameter. Additionally, any desired arm or arms of the instant device may be rendered temporarily inoperative if necessary to utilize the device upon work of irregular polygonal configuration or upon Work of regular polygonal configuration in which the number of sides of the polygon is not a multiple of four.

A related and somewhat more specific object is the provision of a centering device having flexible, rather than rigid, arms in conjunction with a hub including reel means for coiling and uncoiling the arms to retract and extend the outer ends thereof a desired distance from the hub and for maintaining those inactive lengths of the arms housed within the hub.

Another object is the provision of means for alleviating stresses imposed upon the inner ends of the flexible arm members of the instant device during coiling and uncoiling thereof by the reel.

Still other objects will be in part evident and in part pointed out hereinafter in the following description of a preferred embodiment of the invention, which should be read in conjunction with the accompanying drawings, in which:

FIGURE 1 is a top perspective view of the centering device;

FIGURE 2 is a bottom exploded perspective view, in reduced scale, of the device seen in FIGURE 1;

FIGURE 3 is a plan view of the device positioned upon a recessed or sunken work surface of circular configuration;

FIGURE 4 is a horizontal cross-section of the hub structure of the device, taken approximately along line 4-4 of FIGURE 1 and showing the arms in maximum extended position;

FIGURE 5 is a horizontal cross-section of the hub structure of the device similar to FIGURE 4, but on a larger scale and showing the arms in a partially extended position; and

FIGURE 6 is a vertical cross-section taken approximately along line 66 of FIGURE 4.

Referring more particularly to the drawings, the device according to the instant invention shown in FIGURE 1 is identified in its entirety by the numeral 9, and includes a generally cylindrical hub 10, four radial arms 12, and a work engaging jaw or foot 14 of generally L-shaped configuration mounted by rivets 15 upon the outer end of each arm 12 with its greater length extending inwardly beneath the arm toward hub 14 Centering devices of the type thus far generally described are well known and their mode of utilization is understood by those skilled in the art. For this reason, the instant invention is illustrated and described with reference thereto, but it should be understood that no restriction to the specific structure shown is intended for, as will become apparent hereinafter, the invention is applicable to other types of centering devices, for example those having a greater or lesser number of radial arms.

Referring now primarily to FIGURES 2 and 6, hub 10 includes a housing 16 and a base 18, both of generally cup-shaped configuration and each possessing an axial bore 20 in their end walls 21, 23, respectively, and four equally spaced radial slots 22 extending through and longitudinally of their side Walls. The inner diameter of housing 16 is slightly greater than the outer diameter of base 18, permitting these members to be secured together, as by means of screws 19, in closely nested mutually inverted relationship with bores 20 and slots 22in alignment to form the integral generally cylindrical hub 10 shown in FIGURE 1. For a purpose to be discussed subsequently, the cylindrical side wall of hub 10 is relatively thick. 11- lustratively, this is achieved by constructing base 18 with a thicker side wall than housing 16, as shown, but it will be apparent that the same result could be achieved by varying the thicknesses of the side Walls of the base and housing in other ways.

Extending through the aligned bores 20 of hub 16 is a rotatable sleeve or hollow spindle 24, the lower end of which is approximately flush with the outer surface of bottom wall 23 of the hub and the upper end of the sleeve projecting above top wall 21 as shown. Maintaining spindle 24 in this position is a rotatable spool or reel 32 disposed within hub 10 and secured, as by means of a press fit, upon the spindle. Reel 32 has a tubular shaft portion 33, through which spindle 24 extends, and upper and lower radial flange portions 34, 36 at opposite ends thereof. Flanges 34, 36 are in hearing contact with end walls 21, 28, respectively, of hub 10 and. prohibit lateral movement of the reel and spindle while maintaining these members freely rotatable relative to the hub.

To impart rotation to spindle 24 and reel 32, an operating knob 2e receives the projecting upper end of the spindle within its axial bore 23. A set screw 30; rigidly secures the knob to the spindle, so that rotative movement of knob 26 will be transmitted through the spindle to reel 32. The outer surface of knob 26 is knurled or otherwise suitably roughened, as indicated at 31 in FIG- URE 1, to facilitate its manual rotation.

Secured to the upper surface of operating knob 26, as by means of tacks 50, are the two halves of a leaf spring 52, the adjacent ends of which are provided with notches in engagement with a groove 54 extending about the circumference of a punch 56 mounted for longitudinal movement Within spindle 24. Spring 52 resiliently maintains punch 56 in a normally upward position, as shown, in which the lower working end thereof is housed within hub 10 so as to not interfere with placement of face 23 of the device upon a work surface. It will be apparent, however, that once hub 10 is positioned upon a work surface with the punch above the center thereof, in a manner described hereinafter, punch 56 may be readily depressed by means of a hammer blow or the like upon its upper projecting end, so as to permanently record the location of such center.

As best seen in FIGURES 4 and 5, shaft portion 33 of reel 32 has a plurality of longitudinally extending grooves 37 in its periphery. Grooves 37 are spaced ninety degrees from each other, and of such configuration as to define a plurality of tooth-shaped outwardly extending projections 38 which impart a cross-sectional appearance to shaft 33 resembling that of a circular saw blade. Positioned within and extending longitudinally of each groove 37 adjacent its projection 38 is a generally cylindrical pin 40 having a longitudinally extending slot 44 therein. Rivets 42 extend through radial flanges 34, 36 of reel 32 into the ends of pins 40, and secure the same within grooves 37 for rotation with the reel. The connection between rivets 42 and pins 40 is sufficiently loose, however, that each pin is also freely rotatable about its longitudinal axis so as to be capable of movement relative to, as well as with, reel 32.

Arms 12 are positioned within slots 22 of hub 10 and their inner ends are secured, as by welding or through a press fit, within slots 44 of pins 40, as best seen in FIG- URES 4 and 5. Instead of being completely rigid, arms 12 are constructed of sufficiently thin material, for instance metal or plastic, as to possess a flexibility similar to that of the tape of the well known carpenters six-foot measuring device. Also in keeping with such a tape, arms 12 are provided with an arcuate bend to impart additional strength thereto and with indicia of measure 43 along their lengths. The arms 12 thus constructed are sufficiently rigid that their outer end sections bearing foot members 14 radiate linearly outwardly from slots 22 in spoke-like relation to hub 10 lying in a common plane parallel to the plane of face 23, with foot members 14 defining points upon the circumference of an imaginary circle centered about the axis of bore 23 of the hub. Slots 22, by virtue of their heretofore mentioned relatively great length and their having a width only slightly greater than that of arms 12, serve not only to permit passage of arms 12 through the hub, but also guide and maintain the outer end section of the arms in their proper radial positions.

The flexibility of arms 12 enables them to be coiled and uncoiled about reel 32 to vary the radial distance of foot members 14 from hub 10 and the axis of bore 20 thereof. By rotating operating knob 26 in a clockwise direction, thereby simultaneously rotating reel 32 in the same direction, arms 12 are simultaneously and coextensively retracted through slots 22 and coiled about shaft portion 33 of the reel, and/or about the lengths of arms 12 previously collected thereon (see FIGURE Sufficient space is provided between the outer periphery of shaft portion 33 of reel 32 and the inner periphery of hub 10 to accommodate the entire lengths of arms 12, so that the extent to which the arms can be retracted is limited only by abutting of foot members 14 against hub 14). The length of the inwardly directed portions of foot members 14 is such that when this abutting occurs, the free ends of such inwardly directed portions will be adjacent the circumference of bore 24) in the hub, thus permtting utilization of device 9 upon surfaces of extremely small diameter.

Rotation of reel 32 in a counterclockwise direction uncoils arms 12 from about shaft portion 33 and advances them outwardly from hub 10 through slots 22 to extend foot members 14 radially away from the hub and the axis of bore 20. As the arms are advanced through slots 22, the guiding influence of the slots and the inherent resilience of the arms themselves assures that the outer sections thereof both extend and advance linearly from the hub. In their maximum extended condition, illustrated in FIGURES 2 and 4, arms 12 extend linearly inwardly, as well as outwardly, from slots 22 toward the pins 40 securing their inner ends.

It will be noted that in the FIGURE 4 position of arms 12, slots 44 of pins 40 face and are in alignment with slots 22 of hub 10. During initial rotation of reel 32 in a clockwise direction to coil arms 12 upon shaft portion 33, pins 40 are rotated about their axes approximately ninety degrees by the drag of the arms thereon, as shown in FIGURE 5. This slight relative rotation between pins 40 and flange portions 34, 36 of the reel aligns the inner ends of arms 12 secured by the pins with the immediately adjacent sections extending therefrom. This self alignment of the inner ends of arms 12, which also occurs as the arms are completely uncoiled from about the reel, alleviates stresses imposed thereon by rotation of the reel, which stresses would otherwise severely strain the inner ends of the arms and possibly shorten the useful life of device 9.

The mounting of pins 40 within grooves 37 shields them from excessive contact with the arms 12 coiled about shaft portion 33 and prevents binding or locking of the pins. Free rotation of pins 40 in a counterclockwise direction is also assured by the peculiar configuration of the grooves, which curve gradually outwardly on one side toward the periphery of the shaft portion, as shown in FIGURES 4 and 5. The tooth-shaped projections 38 defined between grooves 37 serve to support the coiled arms 12, and thus also prevent undue strain thereof by maintaining the same in substantially circular disposition about the reel.

The basic mode of utilization of device 9 will be ready apparent to those skilled in the art, being similar to that of known centering devices heretofore employed. Unlike the prior devices, however, the device of the instant invention provides the various benefits and advantages heretofore noted. Thus, the capability of the instant device to be reduced in size to a diameter approximately that of hub 10 permits not only facility of storage and handling, but also an enhanced versatility of use. One novel utilization is shown in FIGURE 3, in which device 3 is shown in center locating position upon a work surface 58 which is recessed within and surrounded by an annular rim or edge 60, the diameter of the annular edge 60 being only slightly greater than the diameter of hub 10. The center of such work may be readily located and recorded by the instant device by positioning end face 23 of hub 10 upon surface 58, simultaneously and coextensively retracting arms 12 until foot members 14 each contact the edges of surface 58, as shown, and striking punch 56 with a hammer or the like. Such utilization would not, of course, be possible with centering devices having rigid arms since their overall diameter could not be reduced to a dimension less than one-half the length of any of its arms, which would prohibit placement upon the surface 58 of FIGURE 3.

Another instance in which the instant device demonstrates an enhanced versatility is in conjunction with a work surface which is in'egularly polygonal but has a pair of parallel sides, or regularly polygonal, but having a number of sides not a multiple of four, such as hexagonal. Rigidly constructed centering devices frequently cannot be utilized upon work of this type since the foot members upon some of the arms engage the work surface and prohibit placement of the hub thereon and contact of the other feet with the edges thereof. With the instant device, however, two of the arms 12and the foot members 14 thereon-may be rendered inactive to permit the locating of the center of such work. This is accomplished by merely torsionally flexing two of the arms 12 so as to rotate their feet 14 in an upward direction, while maintaining the lower surface of hub in contact with the work surface and the foot members 14 upon the remaining two arms 12 in contact with the edges thereof. Once the center has been located in this manner and device 9 withdrawn from the work, the flexed arms 12 will readily return to their normal position.

It will thus be seen that the instant invention provides a device in which the various objects and advantages hereinbefore set forth have been achieved, along with many practical benefits.

In the drawings and specification there has been set forth a preferred embodiment of the invention and, although specific terms are employed, they are used in a generic and descriptive sense only and not for purposes of limitation, the scope of the invention being defined in the claims.

That which is claimed is:

1. A device for locating the center of a work surface comprising a hub having a base adapted to be positioned on the work surface and having means defining a plurality of spaced guideways, elongated flexible arm members positioned in said guideways and diverging outwardly from said hub to extend across the work surface, foot members upon the outer end sections of said arm members, said foot members extending through the plane of said base of said hub for engagement with the periphery of the work surface and defining an imaginary circle centered about an axis extending through said hub, reel means carried by said hub and engaging the inner ends of said arms for coiling and uncoiling said arm members, coiling of said arm members by said reel means retracting said foot members toward said axis extending through said hub and uncoiling of said arm members by said reel means extending said arm members away from said axis, whereby the center of various size Work surfaces can be located.

2. A device for locating the center of a work surface comprising a hub adapted to be positioned on the work surface and having means defining a plurality of spaced guideways, means carried by said hub for marking the center of a work surface located by the device, elongated flexible arm members positioned in said guideways and diverging outwardly from said hub to extend across the work surface, foot members upon the outer end sections of said arm members for engagement with the periphery of the Work surface, said foot members defining an imaginary circle about an axis extending through said center marking means, rotatable reel means carried by said sub, the inner ends of said arm members secured to said reel means for rotation therewith, rotation of said reel means in one direction coiling said arm members thereabout to retract said foot members toward said axis extending through said center marking means and rotation of said reel means in the opposite direction uncoiling said arm members from about said reel means to extend said foot members away from said axis, whereby the center of various size work surfaces can be located.

3. A center locating device comprising a hollow hub member having a bore extending therethrough and having openings in its periphery defining a plurality of guideways spaced from and about the axis of said bore, rotatable reel means carried by said hub, elongated flexible arm members positioned in said guideways and extending outwardly from said hub in spoke-like fashion, foot members carried upon the outer end sections of said arm members defining an imaginary circle about the axis of said bore, the inner ends of said arm members secured to said reel means for rotation therewith, rotation of said reel means in one direction coiling said arm members about said reel means to retract said foot members simultaneously and coextensively toward the axis of said bore and rotation in the opposite direction uncoiling said arm members from about said reel means to extend said foot members simultaneously and coextensively away from the axis of said bore, whereby the center of various size work surfaces can be located, and means within said bore for marking the center of a work surface located by the device.

4. A center locating device as in claim 3, wherein said reel means is co-axial with said bore.

5. A center locating device as in claim 3, wherein said arm members are co-planar.

6. A center locating device as in claim 4, wherein said arm members are pivotally secured to said reel means.

7. A center locating device comprising a generally cylindrical hollow hub having an axial bore through opposite ends thereof and a plurality of openings in its periphery defining circumferentially spaced guideways, elongated flexible arm members positioned in said guideways and radiating linearly outwardly from said hub in spoke-like fashion, foot members extending transversely from the outer ends of said arm members and defining an imaginary circle centered about the axis of said bore of said hub, a rotatable reel having a tubular shaft portion between spaced radial flange portions, said reel mounted within said hub with its axis of rotation in alignment with the axis of said bore, the inner ends of said arm members pivotally secured between said flanges of said reel for limited pivotal movement relative thereto and for rotation therewith, rotation of said reel in one direction coiling said arm members about said shaft portion of said reel to retract said foot members simultaneously and coextensively toward said axis of said bore and rotation in the opposite direction uncoiling said arm members from about said shaft portion to extend said foot members simultaneously and coextensively outward from axis, whereby the center of various size work surfaces can be located.

8. A centering device as in claim 7, wherein said shaft portion of said reel has a plurality of spaced grooves extending longitudinally through its periphery, and further including rotatable pin members mounted within said grooves of said reel between said flange portions thereof, the inner ends of said arm members secured to said pin members for limited movement relative to said reel.

9. A centering device as in claim 8, and further including an operating knob rotatably mounted upon said hub and drivably connected to said reel for imparting rotation thereto, said knob having a bore in alignment with the bore of said hub, a center punch mounted for reciprocatory movement through the bores of said knob and hub, and spring means upon said knob engaging and resiliently maintaining said punch in a normally upward position with one end thereof extending above said knob and the other end housed within said hub.

10. A device for locating the center of a work surface comprising a hub adapted to be positioned on the work surface and having means defining a plurality of spaced guide ways, elongated flexible arm members positioned in said guide ways and diverging outwardly from said hub to extend across the work surface, foot members upon the outer end sections of said arm members for engagement with the periphery of the work surface, said foot members defining an imaginary circle about an axis exmembers away from said axis, whereby the center of 10 various size work surfaces can be located, and the limited movement of said inner ends of said arm members relative to said reel means alleviating stresses imposed upon said inner ends by rotation of said reel means.

References Cited in the file of this patent UNITED STATES PATENTS Mays June 11, 1912 Lyon June 13, 1934 

